The present invention relates to solar stills and particularly to a more efficient use of solar energy for the production of fresh water from seawater.
Solar distillation is a well known concept for conversion of seawater into fresh water. Numerous geometric designs have been introduced by various individuals over the past three decades to increase the efficiency of producing and thereby the productivity of fresh water from seawater. However, higher efficiency concepts suffered from higher costs and became economically unattractive and, therefore, uncompetitive. Finally, since the thermodynamics and geometric effects of solar distillation are well understood, it is generally agreed that the simple solar still design has the best immediate potential. Nevertheless, the simple solar still design requires a high ratio of basin area to fresh water production; (10 to 15 ft.sup.2 /1 gallon of fresh water per day). Such a performance has rendered the simple solar still ineffective when compared to conventional means for seawater conversion, i.e. multi-stage flash, vapor compressionn, reverse osmosis, etc.
The present invention is a dramatic improvement over the simple solar still, and uses a double transparent and a double plate heat exchanger through which a working fluid is circulated for first heating the seawater and then condensing the seawater vapor. The distillate is then drawn off as pure water.
It is an object of the invention, therefore, to provide an efficient use of solar energy for the production of fresh water from seawater.
It is also an object of the invention to provide a highly-efficient and non-polluting solar still for producing fresh water from seawater.
Other objects and a more complete appreciation of the present invention and its many attendant advantages will develop as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings in which like reference numerals designate like parts throughout the figures thereof and wherein.